Date:   Sat, 11 Dec 2021 11:50:11 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Bart Van Assche <bvanassche@acm.org>
Cc:     Eric Biggers <ebiggers@kernel.org>, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        linux-scsi@vger.kernel.org, linux-mmc@vger.kernel.org,
        Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH v3 3/3] blk-crypto: show crypto capabilities in sysfs
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References: <20211208013534.136590-1-ebiggers@kernel.org>
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 <6ff4d074-7508-4f4c-de06-f36899668168@acm.org>
 <YbKT/lcp6iZ+lD4n@sol.localdomain>
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On Fri, Dec 10, 2021 at 09:29:41AM -0800, Bart Van Assche wrote:
> On 12/9/21 10:42 PM, Greg Kroah-Hartman wrote:
> > A single hex value makes sense to me.
> 
> Hi Greg,
> 
> I'm not enthusiast about this approach because:
> (a) A single hex value can be confused with a number. Reporting a bitfield in
>     hex format is not sufficient to prevent confusion with a number.

Each sysfs file has their own "units" or values, or whatever.  So a hex
number or bitfield or something else is fine.

Again, single value, no need to parse, is the key here.

> (b) No other block layer sysfs attribute follows this encoding scheme.

Then follow what they do.  Do they have multiple values in a single
file?  If so, they are broken and we should change that.

> (c) This encoding enforces the restriction that data unit sizes are a power of
>     two. Is there anything fundamental in encryption that restricts data unit
>     sizes to a power of two? I don't know the answer myself.

Again, you all can pick the rules you want for this file, if you want to
have bitfields, wonderful!  If you want to make it an enum, wonderful!

thanks,

greg k-h